Means for supplying power on demand



y 3, 1966 M. J. KITTLER 3,248,869

MEANS FOR SUPPLYING POWER ON DEMAND Filed Dec 51, 1964 2 Sheets-Sheet 2L/ l V L F/6. 2 v v INVENTOR M/L 7'0/V J. /(/7' 72 ER ATTORNEY UnitedStates Patent 3,248,869 MEANS FOR SUPPLYING POWER ON DEMAND Milton J.Kittler, Bloomfield Hills, Mich., assignor to Holley Carburetor Company,Warren, Mich., a corporation of Michigan Filed Dec. 31, 1964, Ser. No.422,697 Claims. (Cl. 60-19) This invention relates generally to systemsfor supplying increased power output upon demand, and more particularlyto a system for regulating the speed of an internal combustion enginedriving a hydraulic pump so as to increase engine speed only whenincreased pump output is required.

There are many special types of trucks or other service vehicles wherethe engine that drives the vehicle also drives a pump that supplieshydraulic fluid under pressure to an auxiliary device such as a movableplatform, as disclosed in Troche et al. 2,949,741, the output of thepump being proportional to its speed.

It is desirable and the usual practice, to locate the controls by whichthe operator may move the platform to various positions on the platform.This, of course, re

'quires that the engine driving the pump be operated continuously so asto have hydraulic pressure available at any time that the operator maywant to move the platform.

The engine must, of course, be operated at some speed higher than idlingspeed when pump power output sufficient to operate the hydraulicmechanism is demanded by the operator. However, since the platform isstationary most of the time, increased hydraulic output is demandedduring only' a small fraction of the timethat the platform is in use.Consequently, in order to save wear and tear on the pump and the engine,it is desirable to maintain the engine at idle speed at all times,except when it is desired to operate the hydraulic equipment.

Accordingly, an object of the invention is to provide a system includingan engine-driven pump and adapted to supply increased hydraulic outputupon demand by automatically regulating the speed of the engine betweenpredetermined lower and higher speeds.

Another object of the invention is to provide such a system wherein theengine will operate at the lower speed at all times, except when thehigher speed is required to supply the increased hydraulic output.

Still another object of the invention is to provide such a systemwherein control of the engine is automatically provided by operation ofthe controls for the hydraulic equipment.

Another object of the invention is to provide such a system whereincontrol of said engine is responsive to flow of hydraulic fluid, whetherthe hydraulic equipment be of the rotary hydraulic motor or thehydraulic piston type.

These and other objects and advantages of the invention will become moreapparent upon reference to the following specification and accompanyingdrawings, wherein:

FIGURE 1 is a schematic illustration of anenginedriven hydraulic systemembodying the invention.

FIGURES 2 and 3 are fragmentary portions of FIG- URE 1 illustratingmodifications of the invention.

Referringnow to FIGURE 1, the system 10 includes an internal combustionengine 12 connected to drive a hydraulic pump 14 through thetransmission line 16. The engine 12 may be a separate engine mounted onthe bed of a service type vehicle so as to drive the pump directly, orit may be the same engine that drives the vehicle, in which case itwould be provided with the usual power take off unit for driving thepump 14.

The engine 12 includes an intake manifold 18 fitted with a carburetor20. While the carburetor forms no ice part of the invention, thethrottle control mechanism therefor must be of a particular designadapted to permit the type of automatic control contemplated by theinvention. In FIGURE 1, the carburetor is fitted with the usualpivotally-mounted throttle plate 22 having a lever '24 fixed to thethrottle shaft 26. One end of the lever is urged in a throttle openingdirection by any suitable spring 28 or other resilient means. The extentto which the spring 28 can open the throttle 22 is dependent upon theposition of the abutment 30 adapted to engage the other end 32 of thethrottle lever, the position of the abutment 30 being controlled bymeans such as the operators foot pedal 34. The foot pedal 34 ispivotally mounted at one end 36, and the linkage 38 from the abutment isconnected thereto, the pedal 34 being urged by a spring 40 in adirection to maintain the throttle 22 closed. The end 32- of thethrottle lever 24 has pivotally connected thereto a linkage 42 actuatedby the system 10.

This manner in which the system actuates the linkage 42 will bedescribed, it being sufficient at this time to point out that theabutment 30 may be set to provide some maximum throttle opening, andtherefore a maximum en-- gine speed; however, the system 10 may reducethe engine speed, regardless of the position of the abutment 30, throughthe linkage 42 in opposition to the force of the throttle opening spring28.

The remainder of the system 10 includes the previously mentionedhydraulic pump 14, which may include the usual bypass passage and valvearrangement 44 having a spring 46 for limiting the maximum pressure inthe system 10. The pump 14 delivers hydraulic fluid from the fluidreservoir 48 through the line 50 and discharges it through the line 52to an accumulator 54 which may be employed if it is desired to limitpressure fluctuations in the system 10. From the accumulator 54 thefluid passes through a line 56 to what may be referred to as a demandsensitive switch assembly 58.

The switch assembly 58 comprises a housing 60 formed in any desiredmanner to provide a hydraulic cylinder 62 having an inlet 64 and anoutlet 66. A piston 60 is slidably mounted in the cylinder 62, thepiston having shafts 70 and 72 extending axially from both ends thereof.The shaft 70 extending from the left hand side of the piston 68 passesto the outside of the housing 60 through the opening 74' including-anysuitable dynamic type seal 76 to prevent leakage. The shaft 72 extendingfrom the right hand side of the cylinder is similarly constructed,except that the external free end 78 of the shaft is fitted with amovable type switch contact 80 cooperating with a pair of stationaryswitch contacts 82.

The housing 60 may also be formed with a bypass passage 84 betweenchambers 92 and 94 on the left and right hand sides of the piston 68,the area of the bypass passage being adjustable by means of a screw 86.A compression spring 88 positioned in chamber 94 between the piston 68and the right hand cylinder end wall urges the piston 68 to the left inopposition to any hydraulic pressure urging the piston to the right.

To smooth out the operation of the piston 63, a dashpot mechanism 96 maybe provided against which the shaft must operate. While the particularconstruction of the dashpot 96 is not important, in the constructionshown, the dashpot effect is obtained by the transfer of fluid throughthe adjustable bypass passage 98 between the right and left handchambers 100 and 102 provided by mounting a diaphragm or other movablemember 104 in the housing 106, the spring normally urging the dashpotstem to the right. Adjustment of the bypass is provided by the screw112.

The outlet 66 from the switch assembly 58 communicates through conduit114 with a hydraulic power device 116, such as a hydraulic rotary motor,employed to drive some accessory equipment such as the mobile towershown in the above referenced Troche patent. The line 120 returns thefluid from the hydraulic device back to the fluid reservoir 48. Acontrol valve 118 is included in the line, the purpose of the controlvalve being to either supply or cut ofli hydraulic fluid to thehydraulic device 116.

The previously mentioned linkage 42 pivot-ally connected to the end 32of the throttle lever 24 is secured to the armature 122 of a solenoid124-. An adjustable screw stop 126 limits the travel of the linkage 42in the throttle closing direction when the solenoid is energized byreason of its engagement with an abutment 128 fixed to the linkage 42.The solenoid electric circuit includes a battery 130, the leads 132 and134 and the switch contacts 80 and 82.

OPERATION In operation of a service type vehicle for which the inventionis primarily intended, the vehicle would be parked with the vehicleengine or theauxiliary engine that drives the pump 14 running. In caseof an aerial platform type vehicle, the control valve 118 wouldpreferably be located on the platform itself.

Prior to boarding the platform, the operator would set the abutment 30in any desired manner, such as by the 'stop screw 136, to that enginespeed required for the pump 34 to produce the power output necessary tooperate the hydraulic device 116 and actuate the platform. Then he wouldboard the platform and manually operate the control valve 118 to aposition demanding increased hydraulic output, thereby opening the line114. This will immediately drop the pressure in the chamber 94 to theright of the piston, and the higher pump output pressure in chamber 92to the left of the piston 68 will force the piston to the right againstthe force of the spring 88 until the piston moves past the outlet 66 soas to supply pump output pressure to the device 116. Movement of thepiston to the right will also break the switch contacts 80 and 82,thereby deenergizing the solenoid, thereby permitting the spring 28 tomove the throttle lever 24 in the throttle opening direction until theend 32 thereof engages the previously set abutment 30. This causes theengine 12 to speed up so as to increase the pump 14 speed to provide therequired increased hydraulic output.

When the platform has reached its desired position, the operator closesthe control valve 118, blocking the line 114 and stopping flow to device116. The pressures on opposite sides ofthe piston 68' then becomeequalized by reason of the bypass passage 84, at which time the spring88 return-s the piston 68 to its left most position, against the dashpot96 if one is provided, so as to close the switch contacts 80 and 82.Closing of the contacts again energizes the solenoid so as to move thelinkage 42 to the right until the abutment 128 engages the stop screw126. Th-us,'the engine will again return 'to the predetermined idleoperation.

The pump driving engine 12 must of course be kept running so that theplatform may be moved any time it is desired. However, as stated above,the length of time during which the platform is being moved is a verysmall percentage of the total time that it is in operation. Therefore,it is obvious that considerable wear and tear on the engine 12 and onthe pump 14 is saved by maintaining the engine at an idle speed at alltimes except when higher speed is desired.

' It will be noted that with the use of the system described, the enginespeed control is obtained automatically merely by operating the controlvalve 118 for the hydraulic device 116; no separate engine speed controllevers or other mechanisms are required.

FIGURE 2 is a fragmentary portion of FIGURE 1 illustrating a parallelconnection of two identical hydraulic devices 116 and 116' and theirassociated control valves 118 and 118' between the demand sensitiveswitch assembly 58 and the fluid reservoir 48. Such a parellelarrangement could be employed, for example, where the aerial platformhas mechanisms for both raising and lowering it and for rotating itabout a vertical axis. Other additional parallel-connected hydraulicdevices and control valves could be added if additional movements of theplatform or additional hydraulic power were required for some reason orother.

With such a parallel-connected system, movement of one or more of thecontrol valves, either independently or simultaneously, would result inthe same speed up and subsequent return to idle of the engine 12 and thepump 14.

FIGURE 3 is a fragmentary view simliar to FIGURE 2 except that itillustrates a three-way control valve 136 to accommodate the return ordump line 138, the three-way valve 136 and the line 138 being employedwhere the hydraulic device 116 is a hydraulic piston requiring return ofhydraulic fluid back to the fluid reservoir 48, rather than a continuousflow rotary'rnotor. The threeway valve is also required to lock thepiston in any desired position. Any number of piston type hydraulicdevices and their associated three-way valves may be connected inparallel, similar to the arrangement in FIG- URE 2.

It should be apparent from the above description of its construction andoperation that applicants invention provides a relatively simple,fast-response and foolproof remotely located means for controlling anengine driving a hydraulic pump that supplies a fluid output necessaryto operate hydraulic equipment. Engine and pump Wear are minimizedbecause the engine remains at an idle speed' at all times except when .atemporary higher speed is required. As soon as the demand for increasedhydraulic output is satisfied, the engine automatically returns to theidle speed. The bypass passage 84 is adjusted by means of the screw 86,so that ordinary minimal or leakage flow through the system will notactuate the mechanism; that is, the mechanism will operate only When theoperator demands increased output.

While a preferred embodiment and two modifications of the invention havebeen disclosed, other modifications are possible. For example, it isapparent that any gate type demand valve may be employed in place of thepiston 68, and that the invention is equally adapted to control thespeed of a diesel or other engine for the purpose stated. Also, Whileparallel arrangements are shown, the scope of the invention includes anypossible series arrangements of the hydraulic devices and theirassociated control valves. Thus, no limitations are intended other thanthose recited in the appended claims.

What I claim as my invention is:

1. The combination of an internal combustion engine, a carburetorsupplying motive fluid to said engine and a hydraulic system requiringintermittent periods of high engine speed, said carburetor having athrottle valve urged in the opening direction by resilient means, meansfor limiting the opening movement of said throttle valve to the saidhigh engine speed position, and means working against said resilientmeans urging said throttle valve open for setting said throttle to somepredetermined lower engine speed.

2. The combination of an internal combustion engine; a carburetorsupplying motive fluid to said engine; and a hydraulic system requiringintermittent periods of high engine speed; said carburetor having athrottle valve urged in the opening direction by resilient means, meansfor limiting the opening movement of said throttle valve to the saidhigh engine speed position and means opposing said resilient means forurging said throttle valve open for setting said throttle to somepredetermined lower engine speed; said system including ahydraulically-operated device, a fluid reservoir, a hydraulic pumpdriven by said engine, a control valve for supplying and Cutting offfluid pressure from said pump to said hydraulic device, suitablehydraulic conditions connecting the above elements of said system, and afluid flow responsive piston assembly connected in one of said conduits,said assembly including means adapted during periods when hydraulicfluid is not flowing in said system for actuating said opposing meansfor reducing engine speed to said lower speed.

3. The combination of an internal combustion engine; a carburetorsupplying motive fluid to said engine; and a hydraulic system requiringintermittent periods of high engine speed; said carburetor having athrottle valve urged in the opening direction by resilient means, meansfor limiting the opening movement of said throttle valve to the saidhigh engine speed position and means opposing said resilient means forurging said throttle valve open for setting said throttle to somepredetermined lower engine speed; said system including ahydraulically-operated device, a fluid reservoir, a hydraulic pumpdriven by said engine, a control valve for supplying and cutting offfluid pressure from said pump to said hydraulic device, suitablehydraulic conduits connecting the above elements of said system, and afluid flow responsive piston assembly connected in one of said conduits,said assembly including means adapted during periods when hydraulicfluid is flowing in said system for allowing said resilient means toopen said throttle to said high speed.

4. The combination recited in claim 2, wherein said latter meanscomprises an electrical circuit including a switch actuated by saidpiston assembly and a solenoid for moving said throttle to said lowerspeed when said switch is closed.

5. The structure recited in claim 2, wherein said hydraulic device is ofthe piston type and said control valve is a three-way valve so that saidpiston may be actuated, locked in any position and returned.

6. In an internal combustion engine having a fuel control systemincluding a throttle valve, a hydraulically operated device, means foroperating said device and means for regulating the position of saidthrottle valve, said last mentioned means comprising a circuit includinga stationary contact, a solenoid, a movable contact operated by saidfirst mentioned means, and linkage means between said solenoid and saidthrottle valve.

7. In an internal combustion engine having a fuel control systemincluding a throttle valve, a hydraulically operated device and meansfor operating said device and for regulating the position of saidthrottle valve, said means including a hydraulic pump driven by saidengine, a

hydraulically operated piston, a first conduit communicating betweensaid pump and one side of said piston, a second conduit communicatingbetween the other side of said piston and said hydraulically operateddevice, a control valve in said second conduit for opening said secondconduit and thereby decreasing the pressure adjacent said other side ofsaid piston and causing said piston to move so as to permit directcommunication between said first and said second conduits, and meansactuated by movement of said piston for regulating the position of saidthrottle valve.

8. The device described in claim 7, wherein said last mentioned meanscomprises a circuit including a stationary contact, a movable contactoperated by said piston and a solenoid, and linkage means between saidsolenoid and said throttle valve.

9. The combination of an internal combustion engine supplied with motivefluid by a fuel control system including modulating means for varyingthe amount of said fluid, a hydraulic pump driven by said engine, ahydraulically operated device, a conduitry system communicating betweensaid pump and said device, a control valve in said conduitry system, apiston in said conduitry system, said piston being movable in responseto opening of said control valve for permitting said fluid to flow tosaid device and cause it to operate, a solenoid, linkage means connectedbetween said solenoid and said modulating means, and an electricalswitch operatively connected to said solenoid and to said piston, saidswitch being actuated by movement of said piston for causing saidsolenoid to reposition said modulating means through said linkage means.

10. The combination of claim 9, wherein additional means are provided tolimit the open position of said modulating means.

References Cited by the Examiner UNITED STATES PATENTS 2,170,890 8/1939Allen 51 X 2,354,634 7/1944 Griswold 137501 2,772,409 11/1956 Reid20081.9 X 2,853,575 9/1958 Reynolds 20081.9 2,931,305 4/1960 Stratton6()19 X 2,941,365 6/1960 Carlson et a1. 6019 X 2,984,985 5/1961MacMillin 6()52 X 3,036,435 5/1962 Samuely 60- l9 X EDGAR W. GEOGHEGAN,Primary Examiner.

1. THE COMBINATION OF AN INTERNAL COMBUSTION ENGINE, A CARBURETORSUPPLYING MOTIVE FLUID TO SAID ENGINE AND A HYDRAULIC SYSTEM REQUIRINGINTERMITTENT PERIODS OF HIGH ENGING SPEED, SAID CARBURETOR HAVING ATHROTTLE VALVE URGED IN THE OPENING DIRECTION BY RESILIENT MEANS, MEANSFOR LIMITING THE OPENING MOVEMENT OF SAID THROTTLE VALVE TO THE SAIDHIGH ENGINE SPEED POSITION, AND MEANS WORKING AGAINST SAID RESILIENTMEANS URGING SAID THROTTLE VALVE OPEN FOR SETTING SAID THROTTLE TO SOMEPREDETERMINED LOWER ENGINE SPEED.